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( Nishi et al., 2003 ). Aap of EAEC is secreted by many EAEC strains and was sug-
gested as a possible target for diagnosis ( Sheikh et al., 2002 ). However, a recent
report demonstrates that Aap is also produced by non-EAEC strain. A multiplex
PCR assay was developed that detects the three AA plasmid-borne genes ( aatA,
aggR, and aap ) and studies showed that these loci are commonly but not invari-
ably linked ( Opintan et al., 2010 ). The authors of this study found that 82% of the
EAEC strains isolated from patients with diarrhea were positive for the three loci
and that use of a multiplex assay increases both the sensitivity and the specific-
ity of EAEC detection ( Cerna et al., 2003 ). Several studies have applied PCR in
detecting EAEC targeting genes aggR and/or aatA ( Kahali et al., 2004 ; Sarantuya
et al., 2004 ; Pereira et al., 2007 ; Regua-Mangia et al., 2009 ; Gomez-Duarte et al.,
2010 ; Opintan et al., 2010 ; Rugeles et al., 2010 ). The variable results obtained
using molecular diagnostics may be due to the heterogeneity in EAEC pathogenic
mechanisms ( Okeke and Nataro, 2001 ). PCR targeting both virulence factors on
the pAA plasmid and the chromosomal EAEC loci, such as aaiC ( Dudley et al.,
2006 ) might prove to be the most advantageous approach in detecting EAEC.
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